package wx.xml.stax.api.stream;

import wx.xml.stax.api.namespace.NamespaceContext;
import wx.xml.stax.api.namespace.QName;

/**
 * The XMLStreamReader interface allows forward, read-only access to XML.
 * It is designed to be the lowest level and most efficient way to
 * read XML data.
 *
 * <p> The XMLStreamReader is designed to iterate over XML using
 * next() and hasNext().  The data can be accessed using methods such as getEventType(),
 * getNamespaceURI(), getLocalName() and getText();
 *
 * <p> The <a href="#next()">next()</a> method causes the reader to read the next parse event.
 * The next() method returns an integer which identifies the type of event just read.
 * <p> The event type can be determined using <a href="#getEventType()">getEventType()</a>.
 * <p> Parsing events are defined as the XML Declaration, a DTD,
 * start tag, character data, white space, end tag, comment,
 * or processing instruction.  An attribute or namespace event may be encountered
 * at the root level of a document as the result of a query operation.
 *
 * <p>For XML 1.0 compliance an XML processor must pass the
 * identifiers of declared unparsed entities, notation declarations and their
 * associated identifiers to the application.  This information is
 * provided through the property API on this interface.
 * The following two properties allow access to this information:
 * wx.xml.stax.api.stream.notations and wx.xml.stax.api.stream.entities.
 * When the current event is a DTD the following call will return a
 * list of Notations
 * <code>List l = (List) getProperty("javax.xml.stream.notations");</code>
 * The following call will return a list of entity declarations:
 * <code>List l = (List) getProperty("javax.xml.stream.entities");</code>
 * These properties can only be accessed during a DTD event and
 * are defined to return null if the information is not available.
 *
 * <p>The following table describes which methods are valid in what state.
 * If a method is called in an invalid state the method will throw a
 * java.lang.IllegalStateException.
 *
 * <table border="2" rules="all" cellpadding="4">
 * <thead>
 * <tr>
 * <th align="center" colspan="2">
 * Valid methods for each state
 * </th>
 * </tr>
 * </thead>
 * <tbody>
 * <tr>
 * <th>Event Type</th>
 * <th>Valid Methods</th>
 * </tr>
 * <tr>
 * <td> All States  </td>
 * <td> getProperty(), hasNext(), require(), close(),
 * getNamespaceURI(), isStartElement(),
 * isEndElement(), isCharacters(), isWhiteSpace(),
 * getNamespaceContext(), getEventType(),getLocation(),
 * hasText(), hasName()
 * </td>
 * </tr>
 * <tr>
 * <td> START_ELEMENT  </td>
 * <td> next(), getName(), getLocalName(), hasName(), getPrefix(),
 * getAttributeXXX(), isAttributeSpecified(),
 * getNamespaceXXX(),
 * getElementText(), nextTag()
 * </td>
 * </tr>
 * <td> ATTRIBUTE  </td>
 * <td> next(), nextTag()
 * getAttributeXXX(), isAttributeSpecified(),
 * </td>
 * </tr>
 * </tr>
 * <td> NAMESPACE  </td>
 * <td> next(), nextTag()
 * getNamespaceXXX()
 * </td>
 * </tr>
 * <tr>
 * <td> END_ELEMENT  </td>
 * <td> next(), getName(), getLocalName(), hasName(), getPrefix(),
 * getNamespaceXXX(), nextTag()
 * </td>
 * </tr>
 * <tr>
 * <td> CHARACTERS  </td>
 * <td> next(), getTextXXX(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> CDATA  </td>
 * <td> next(), getTextXXX(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> COMMENT  </td>
 * <td> next(), getTextXXX(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> SPACE  </td>
 * <td> next(), getTextXXX(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> START_DOCUMENT  </td>
 * <td> next(), getEncoding(), getVersion(), isStandalone(), standaloneSet(),
 * getCharacterEncodingScheme(), nextTag()</td>
 * </tr>
 * <tr>
 * <td> END_DOCUMENT  </td>
 * <td> close()</td>
 * </tr>
 * <tr>
 * <td> PROCESSING_INSTRUCTION  </td>
 * <td> next(), getPITarget(), getPIData(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> ENTITY_REFERENCE  </td>
 * <td> next(), getLocalName(), getText(), nextTag() </td>
 * </tr>
 * <tr>
 * <td> DTD  </td>
 * <td> next(), getText(), nextTag() </td>
 * </tr>
 * </tbody>
 * </table>
 *
 * @author Copyright (c) 2003 by BEA Systems. All Rights Reserved.
 * @version 1.0
 * @see wx.xml.stax.api.stream.events.XMLEvent
 * @see XMLInputFactory
 * @see XMLStreamWriter
 */
public interface XMLStreamReader extends XMLStreamConstants {
    /**
     * Get the value of a feature/property from the underlying implementation
     *
     * @param name The name of the property, may not be null
     * @return The value of the property
     * @throws IllegalArgumentException if name is null
     */
    public Object getProperty(java.lang.String name) throws java.lang.IllegalArgumentException;

    /**
     * Get next parsing event - a processor may return all contiguous
     * character data in a single chunk, or it may split it into several chunks.
     * If the property wx.xml.stax.api.stream.isCoalescing is set to true
     * element content must be coalesced and only one CHARACTERS event
     * must be returned for contiguous element content or
     * CDATA Sections.
     * <p>
     * By default entity references must be
     * expanded and reported transparently to the application.
     * An exception will be thrown if an entity reference cannot be expanded.
     * If element content is empty (i.e. content is "") then no CHARACTERS event will be reported.
     *
     * <p>Given the following XML:<br>
     * &lt;foo>&lt;!--description-->content text&lt;![CDATA[&lt;greeting>Hello&lt;/greeting>]]>other content&lt;/foo><br>
     * The behavior of calling next() when being on foo will be:<br>
     * 1- the comment (COMMENT)<br>
     * 2- then the characters section (CHARACTERS)<br>
     * 3- then the CDATA section (another CHARACTERS)<br>
     * 4- then the next characters section (another CHARACTERS)<br>
     * 5- then the END_ELEMENT<br>
     *
     * <p><b>NOTE:</b> empty element (such as &lt;tag/>) will be reported
     * with  two separate events: START_ELEMENT, END_ELEMENT - This preserves
     * parsing equivalency of empty element to &lt;tag>&lt;/tag>.
     * <p>
     * This method will throw an IllegalStateException if it is called after hasNext() returns false.
     *
     * @return the integer code corresponding to the current parse event
     * @throws NoSuchElementException if this is called when hasNext() returns false
     * @throws XMLStreamException     if there is an error processing the underlying XML source
     * @see wx.xml.stax.api.stream.events.XMLEvent
     */
    public int next() throws XMLStreamException;

    /**
     * Test if the current event is of the given type and if the namespace and name match the current
     * namespace and name of the current event.  If the namespaceURI is null it is not checked for equality,
     * if the localName is null it is not checked for equality.
     *
     * @param type         the event type
     * @param namespaceURI the uri of the event, may be null
     * @param localName    the localName of the event, may be null
     * @throws XMLStreamException if the required values are not matched.
     */
    public void require(int type, String namespaceURI, String localName) throws XMLStreamException;

    /**
     * Reads the content of a text-only element, an exception is thrown if this is
     * not a text-only element.
     * Regardless of value of wx.xml.stax.api.stream.isCoalescing this method always returns coalesced content.
     * <br /> Precondition: the current event is START_ELEMENT.
     * <br /> Postcondition: the current event is the corresponding END_ELEMENT.
     * <p>
     * <br />The method does the following (implementations are free to optimized
     * but must do equivalent processing):
     * <pre>
     * if(getEventType() != XMLStreamConstants.START_ELEMENT) {
     * throw new XMLStreamException(
     * "parser must be on START_ELEMENT to read next text", getLocation());
     * }
     * int eventType = next();
     * StringBuffer content = new StringBuffer();
     * while(eventType != XMLStreamConstants.END_ELEMENT ) {
     * if(eventType == XMLStreamConstants.CHARACTERS
     * || eventType == XMLStreamConstants.CDATA
     * || eventType == XMLStreamConstants.SPACE
     * || eventType == XMLStreamConstants.ENTITY_REFERENCE) {
     * buf.append(getText());
     * } else if(eventType == XMLStreamConstants.PROCESSING_INSTRUCTION
     * || eventType == XMLStreamConstants.COMMENT) {
     * // skipping
     * } else if(eventType == XMLStreamConstants.END_DOCUMENT) {
     * throw new XMLStreamException(
     * "unexpected end of document when reading element text content", this);
     * } else if(eventType == XMLStreamConstants.START_ELEMENT) {
     * throw new XMLStreamException(
     * "element text content may not contain START_ELEMENT", getLocation());
     * } else {
     * throw new XMLStreamException(
     * "Unexpected event type "+eventType, getLocation());
     * }
     * eventType = next();
     * }
     * return buf.toString();
     * </pre>
     *
     * @throws XMLStreamException if the current event is not a START_ELEMENT
     *                            or if a non text element is encountered
     */
    public String getElementText() throws XMLStreamException;

    /**
     * Skips any white space (isWhiteSpace() returns true), COMMENT,
     * or PROCESSING_INSTRUCTION,
     * until a START_ELEMENT or END_ELEMENT is reached.
     * If other than white space characters, COMMENT, PROCESSING_INSTRUCTION, START_ELEMENT, END_ELEMENT
     * are encountered, an exception is thrown. This method should
     * be used when processing element-only content seperated by white space.
     * <p>
     * <br /> Precondition: none
     * <br /> Postcondition: the current event is START_ELEMENT or END_ELEMENT
     * and cursor may have moved over any whitespace event.
     * <p>
     * <br />Essentially it does the following (implementations are free to optimized
     * but must do equivalent processing):
     * <pre>
     * int eventType = next();
     * while((eventType == XMLStreamConstants.CHARACTERS &amp;&amp; isWhiteSpace()) // skip whitespace
     * || (eventType == XMLStreamConstants.CDATA &amp;&amp; isWhiteSpace())
     * // skip whitespace
     * || eventType == XMLStreamConstants.SPACE
     * || eventType == XMLStreamConstants.PROCESSING_INSTRUCTION
     * || eventType == XMLStreamConstants.COMMENT
     * ) {
     * eventType = next();
     * }
     * if (eventType != XMLStreamConstants.START_ELEMENT &amp;&amp; eventType != XMLStreamConstants.END_ELEMENT) {
     * throw new String XMLStreamException("expected start or end tag", getLocation());
     * }
     * return eventType;
     * </pre>
     *
     * @return the event type of the element read (START_ELEMENT or END_ELEMENT)
     * @throws XMLStreamException     if the current event is not white space, PROCESSING_INSTRUCTION,
     *                                START_ELEMENT or END_ELEMENT
     * @throws NoSuchElementException if this is called when hasNext() returns false
     */
    public int nextTag() throws XMLStreamException;

    /**
     * Returns true if there are more parsing events and false
     * if there are no more events.  This method will return
     * false if the current state of the XMLStreamReader is
     * END_DOCUMENT
     *
     * @return true if there are more events, false otherwise
     * @throws XMLStreamException if there is a fatal error detecting the next state
     */
    public boolean hasNext() throws XMLStreamException;

    /**
     * Frees any resources associated with this Reader.  This method does not close the
     * underlying input source.
     *
     * @throws XMLStreamException if there are errors freeing associated resources
     */
    public void close() throws XMLStreamException;

    /**
     * Return the uri for the given prefix.
     * The uri returned depends on the current state of the processor.
     *
     * <p><strong>NOTE:</strong>The 'xml' prefix is bound as defined in
     * <a href="http://www.w3.org/TR/REC-xml-names/#ns-using">Namespaces in XML</a>
     * specification to "http://www.w3.org/XML/1998/namespace".
     *
     * <p><strong>NOTE:</strong> The 'xmlns' prefix must be resolved to following namespace
     * <a href="http://www.w3.org/2000/xmlns/">http://www.w3.org/2000/xmlns/</a>
     *
     * @param prefix The prefix to lookup, may not be null
     * @return the uri bound to the given prefix or null if it is not bound
     * @throws IllegalArgumentException if the prefix is null
     */
    public String getNamespaceURI(String prefix);

    /**
     * Returns true if the cursor points to a start tag (otherwise false)
     *
     * @return true if the cursor points to a start tag, false otherwise
     */
    public boolean isStartElement();

    /**
     * Returns true if the cursor points to an end tag (otherwise false)
     *
     * @return true if the cursor points to an end tag, false otherwise
     */
    public boolean isEndElement();

    /**
     * Returns true if the cursor points to a character data event
     *
     * @return true if the cursor points to character data, false otherwise
     */
    public boolean isCharacters();

    /**
     * Returns true if the cursor points to a character data event
     * that consists of all whitespace
     *
     * @return true if the cursor points to all whitespace, false otherwise
     */
    public boolean isWhiteSpace();


    /**
     * Returns the normalized attribute value of the
     * attribute with the namespace and localName
     * If the namespaceURI is null the namespace
     * is not checked for equality
     *
     * @param namespaceURI the namespace of the attribute
     * @param localName    the local name of the attribute, cannot be null
     * @return returns the value of the attribute , returns null if not found
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributeValue(String namespaceURI,
                                    String localName);

    /**
     * Returns the count of attributes on this START_ELEMENT,
     * this method is only valid on a START_ELEMENT or ATTRIBUTE.  This
     * count excludes namespace definitions.  Attribute indices are
     * zero-based.
     *
     * @return returns the number of attributes
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public int getAttributeCount();

    /**
     * Returns the qname of the attribute at the provided index
     *
     * @param index the position of the attribute
     * @return the QName of the attribute
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public QName getAttributeName(int index);

    /**
     * Returns the namespace of the attribute at the provided
     * index
     *
     * @param index the position of the attribute
     * @return the namespace URI (can be null)
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributeNamespace(int index);

    /**
     * Returns the localName of the attribute at the provided
     * index
     *
     * @param index the position of the attribute
     * @return the localName of the attribute
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributeLocalName(int index);

    /**
     * Returns the prefix of this attribute at the
     * provided index
     *
     * @param index the position of the attribute
     * @return the prefix of the attribute
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributePrefix(int index);

    /**
     * Returns the XML type of the attribute at the provided
     * index
     *
     * @param index the position of the attribute
     * @return the XML type of the attribute
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributeType(int index);

    /**
     * Returns the value of the attribute at the
     * index
     *
     * @param index the position of the attribute
     * @return the attribute value
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public String getAttributeValue(int index);

    /**
     * Returns a boolean which indicates if this
     * attribute was created by default
     *
     * @param index the position of the attribute
     * @return true if this is a default attribute
     * @throws IllegalStateException if this is not a START_ELEMENT or ATTRIBUTE
     */
    public boolean isAttributeSpecified(int index);

    /**
     * Returns the count of namespaces declared on this START_ELEMENT or END_ELEMENT,
     * this method is only valid on a START_ELEMENT, END_ELEMENT or NAMESPACE. On
     * an END_ELEMENT the count is of the namespaces that are about to go
     * out of scope.  This is the equivalent of the information reported
     * by SAX callback for an end element event.
     *
     * @return returns the number of namespace declarations on this specific element
     * @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
     */
    public int getNamespaceCount();

    /**
     * Returns the prefix for the namespace declared at the
     * index.  Returns null if this is the default namespace
     * declaration
     *
     * @param index the position of the namespace declaration
     * @return returns the namespace prefix
     * @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
     */
    public String getNamespacePrefix(int index);

    /**
     * Returns the uri for the namespace declared at the
     * index.
     *
     * @param index the position of the namespace declaration
     * @return returns the namespace uri
     * @throws IllegalStateException if this is not a START_ELEMENT, END_ELEMENT or NAMESPACE
     */
    public String getNamespaceURI(int index);

    /**
     * Returns a read only namespace context for the current
     * position.  The context is transient and only valid until
     * a call to next() changes the state of the reader.
     *
     * @return return a namespace context
     */
    public NamespaceContext getNamespaceContext();

    /**
     * Returns a reader that points to the current start element
     * and all of its contents.  Throws an XMLStreamException if the
     * cursor does not point to a START_ELEMENT.<p>
     * The sub stream is read from it MUST be read before the parent stream is
     * moved on, if not any call on the sub stream will cause an XMLStreamException to be
     * thrown.   The parent stream will always return the same result from next()
     * whatever is done to the sub stream.
     * @return an XMLStreamReader which points to the next element
     */
    //  public XMLStreamReader subReader() throws XMLStreamException;

    /**
     * Allows the implementation to reset and reuse any underlying tables
     */
    //  public void recycle() throws XMLStreamException;

    /**
     * Returns an integer code that indicates the type
     * of the event the cursor is pointing to.
     */
    public int getEventType();

    /**
     * Returns the current value of the parse event as a string,
     * this returns the string value of a CHARACTERS event,
     * returns the value of a COMMENT, the replacement value
     * for an ENTITY_REFERENCE, the string value of a CDATA section,
     * the string value for a SPACE event,
     * or the String value of the internal subset of the DTD.
     * If an ENTITY_REFERENCE has been resolved, any character data
     * will be reported as CHARACTERS events.
     *
     * @return the current text or null
     * @throws java.lang.IllegalStateException if this state is not
     *                                         a valid text state.
     */
    public String getText();

    /**
     * Returns an array which contains the characters from this event.
     * This array should be treated as read-only and transient. I.e. the array will
     * contain the text characters until the XMLStreamReader moves on to the next event.
     * Attempts to hold onto the character array beyond that time or modify the
     * contents of the array are breaches of the contract for this interface.
     *
     * @return the current text or an empty array
     * @throws java.lang.IllegalStateException if this state is not
     *                                         a valid text state.
     */
    public char[] getTextCharacters();

    /**
     * Gets the the text associated with a CHARACTERS, SPACE or CDATA event.
     * Text starting a "sourceStart" is copied into "target" starting at "targetStart".
     * Up to "length" characters are copied.  The number of characters actually copied is returned.
     * <p>
     * The "sourceStart" argument must be greater or equal to 0 and less than or equal to
     * the number of characters associated with the event.  Usually, one requests text starting at a "sourceStart" of 0.
     * If the number of characters actually copied is less than the "length", then there is no more text.
     * Otherwise, subsequent calls need to be made until all text has been retrieved. For example:
     *
     * <code>
     * int length = 1024;
     * char[] myBuffer = new char[ length ];
     * <p>
     * for ( int sourceStart = 0 ; ; sourceStart += length )
     * {
     * int nCopied = stream.getTextCharacters( sourceStart, myBuffer, 0, length );
     * <p>
     * if (nCopied < length)
     * break;
     * }
     * </code>
     * XMLStreamException may be thrown if there are any XML errors in the underlying source.
     * The "targetStart" argument must be greater than or equal to 0 and less than the length of "target",
     * Length must be greater than 0 and "targetStart + length" must be less than or equal to length of "target".
     *
     * @param sourceStart the index of the first character in the source array to copy
     * @param target      the destination array
     * @param targetStart the start offset in the target array
     * @param length      the number of characters to copy
     * @return the number of characters actually copied
     * @throws XMLStreamException            if the underlying XML source is not well-formed
     * @throws IndexOutOfBoundsException     if targetStart < 0 or > than the length of target
     * @throws IndexOutOfBoundsException     if length < 0 or targetStart + length > length of target
     * @throws UnsupportedOperationException if this method is not supported
     * @throws NullPointerException          is if target is null
     */
    public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length)
        throws XMLStreamException;

    /**
     * Gets the text associated with a CHARACTERS, SPACE or CDATA event.  Allows the underlying
     * implementation to return the text as a stream of characters.  The reference to the
     * Reader returned by this method is only valid until next() is called.
     *
     * All characters must have been checked for well-formedness.
     *
     * <p> This method is optional and will throw UnsupportedOperationException if it is not supported.
     * @throws UnsupportedOperationException if this method is not supported
     * @throws IllegalStateException if this is not a valid text state
     */
    //public Reader getTextStream();

    /**
     * Returns the offset into the text character array where the first
     * character (of this text event) is stored.
     *
     * @throws java.lang.IllegalStateException if this state is not
     *                                         a valid text state.
     */
    public int getTextStart();

    /**
     * Returns the length of the sequence of characters for this
     * Text event within the text character array.
     *
     * @throws java.lang.IllegalStateException if this state is not
     *                                         a valid text state.
     */
    public int getTextLength();

    /**
     * Return input encoding if known or null if unknown.
     *
     * @return the encoding of this instance or null
     */
    public String getEncoding();

    /**
     * Return true if the current event has text, false otherwise
     * The following events have text:
     * CHARACTERS,DTD ,ENTITY_REFERENCE, COMMENT, SPACE
     */
    public boolean hasText();

    /**
     * Return the current location of the processor.
     * If the Location is unknown the processor should return
     * an implementation of Location that returns -1 for the
     * location and null for the publicId and systemId.
     * The location information is only valid until next() is
     * called.
     */
    public Location getLocation();

    /**
     * Returns a QName for the current START_ELEMENT or END_ELEMENT event
     *
     * @return the QName for the current START_ELEMENT or END_ELEMENT event
     * @throws IllegalStateException if this is not a START_ELEMENT or
     *                               END_ELEMENT
     */
    public QName getName();

    /**
     * Returns the (local) name of the current event.
     * For START_ELEMENT or END_ELEMENT returns the (local) name of the current element.
     * For ENTITY_REFERENCE it returns entity name.
     * The current event must be START_ELEMENT or END_ELEMENT,
     * or ENTITY_REFERENCE
     *
     * @return the localName
     * @throws IllegalStateException if this not a START_ELEMENT,
     *                               END_ELEMENT or ENTITY_REFERENCE
     */
    public String getLocalName();

    /**
     * returns true if the current event has a name (is a START_ELEMENT or END_ELEMENT)
     * returns false otherwise
     */
    public boolean hasName();

    /**
     * If the current event is a START_ELEMENT or END_ELEMENT  this method
     * returns the URI of the prefix or the default namespace.
     * Returns null if the event does not have a prefix.
     *
     * @return the URI bound to this elements prefix, the default namespace, or null
     */
    public String getNamespaceURI();

    /**
     * Returns the prefix of the current event or null if the event does not have a prefix
     *
     * @return the prefix or null
     */
    public String getPrefix();

    /**
     * Get the xml version declared on the xml declaration
     * Returns null if none was declared
     *
     * @return the XML version or null
     */
    public String getVersion();

    /**
     * Get the standalone declaration from the xml declaration
     *
     * @return true if this is standalone, or false otherwise
     */
    public boolean isStandalone();

    /**
     * Checks if standalone was set in the document
     *
     * @return true if standalone was set in the document, or false otherwise
     */
    public boolean standaloneSet();

    /**
     * Returns the character encoding declared on the xml declaration
     * Returns null if none was declared
     *
     * @return the encoding declared in the document or null
     */
    public String getCharacterEncodingScheme();

    /**
     * Get the target of a processing instruction
     *
     * @return the target or null
     */
    public String getPITarget();

    /**
     * Get the data section of a processing instruction
     *
     * @return the data or null
     */
    public String getPIData();
}




